JP2001071643A - Reversible heat-sensitive recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversible heat-sensitive recording medium having good high-speed erasing characteristics and to obtain the recording medium having good color developing characteristics and preserving characteristics, no notch of the medium even by repeatedly using, good durability and good light resistance against an ultraviolet ray. SOLUTION: The reversible heat-sensitive recording medium comprises a reversible heat-sensitive recording layer containing a compound represented by the formula as an achromatization accelerator, wherein n is an integer of 2 to 4, R1 is a 1-20C hydrocarbon group or 1-6 a bonding hands, R2 is 1-20C hydrocarbon group, and X is bivalent group containing a hetero atom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible thermosensitive coloring composition utilizing a coloring reaction between an electron-donating color-forming compound and an electron-accepting compound. The present invention relates to a reversible thermosensitive recording medium capable of forming and erasing.

[0002]

2. Description of the Related Art Conventionally, an electron-donating color-forming compound (hereinafter, referred to as an electron donating color compound)
Thermal recording media utilizing a color development reaction between a color former or a leuco dye and an electron-accepting compound (hereinafter also referred to as a developer) are widely known, such as facsimile machines, word processors, and scientific measuring instruments. Used in printers. However, these conventional recording media that have been put into practical use all have irreversible color development, and once recorded images cannot be erased and used repeatedly.

On the other hand, many patent publications have proposed recording media capable of reversibly developing and erasing colors.
For example, those using a combination of gallic acid and phloroglucinol as a color developer (Japanese Patent Application Laid-Open No. 60-193691), those using a compound such as phenolphthalein or thymolphthalein as a color developer (Japanese Patent Application Laid-Open No. 61-1986) -237
No. 684), a recording layer containing a homogeneous solution of a color former, a developer and a carboxylic acid ester (Japanese Patent Laid-Open No. 62-1).
38556, JP-A-62-138568 and JP-A-62-140881), and those using an ascorbic acid derivative as a color developing agent (JP-A-63-1736).
No. 84), and those using bis (hydroxyphenyl) acetic acid or a salt of gallic acid and a higher aliphatic amine as a color developing agent (JP-A-2-188293 and JP-A-2-2-1).
No. 88294).

Further, the present inventors have disclosed in Japanese Patent Laid-Open No.
No. 4360, an organic phosphoric acid compound, an aliphatic carboxylic acid compound or a phenol compound having a long-chain aliphatic hydrocarbon group is used as a color developer, and the color is developed and decolored by combining this with a leuco dye as a color former. Can be easily performed by heating and cooling conditions, and its color-developed state and decolored state can be stably maintained at room temperature. In addition, a reversible thermosensitive coloring composition capable of repeating coloring and decoloring. And a reversible thermosensitive recording medium using the same in the recording layer were proposed. Thereafter, the use of a specific structure for a phenol compound having a long-chain aliphatic hydrocarbon group has been proposed (JP-A-6-21095).
No. 4).

However, if printing and erasing are repeatedly performed under actual use conditions, problems such as a decrease in image density and bleeding (deformation of a printed portion) may occur, and the color development and development of the developer and leuco dye composition may occur. A reversible thermosensitive recording medium capable of sufficiently exhibiting the decoloring characteristics has not been obtained. This is because printing by the thermal head is performed while applying mechanical force to the recording medium simultaneously with heating to a high temperature, so the structure of the layers that make up the recording medium, such as the recording layer and protective layer, changes, and It is due to being destroyed.

In order to solve such a problem of the recording medium, Japanese Patent Application Laid-Open No. Hei 6-340171 proposes improvement of the repetition durability by adding particles having an average particle diameter of 1.1 times or more the thickness of the recording layer. Japanese Patent Application Laid-Open No. 8-156410 proposes improvement of repetition durability by improving head matching by providing a protective layer having glossiness and surface roughness of characteristics.

However, even if these recording layers and protective layers are used, it is not possible to completely prevent the destruction of the coating layer during repeated printing and erasing. This causes a printing defect or the like, and has a problem that the number of times of repeated use is substantially limited to a small number.

[0008] Furthermore, in actual use, since it is often stored under light irradiation, it must be high in light resistance and must not deteriorate the color development / decoloration characteristics due to light.
However, in practice, when the printed image area and the background area are exposed to light such as fluorescent light and sunlight for a long time, the printed image area and the background area are discolored. In particular, the printed image area is completely erased even if the image is erased. However, there is a problem that an afterimage occurs without performing the above operation.

Further, Japanese Patent Laid-Open Publication No. 8-310128,
JP-A-9-272262, JP-A-9-27056
No. 3, JP-A-9-300817, JP-A-9-300817
Japanese Patent Application Laid-Open No. 300820 discloses that by adding a specific decoloring accelerator, it is possible to obtain high-speed erasing characteristics. However, by changing an electron-accepting compound and a binder that cause a reversible color tone change, There are problems that the image density at the time of erasing is practically high, and that the erasing start temperature and the erasing temperature range are not improved.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reversible thermosensitive recording medium having good high-speed erasing characteristics. Further, the recording medium has good coloring and storage characteristics, and can be used repeatedly. It is an object of the present invention to provide a reversible thermosensitive recording medium having good durability and good light resistance to ultraviolet light without occurrence of dents.

[0011]

Means for Solving the Problems The present inventors use an electron-donating color-forming compound and an electron-accepting compound on a support, and adjust the relative heating temperature and / or the cooling rate after heating. In a reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing a reversible thermochromic composition capable of forming a colored state and a decolored state, as a result of intensive studies to solve the above problems, Since the reversible thermosensitive recording layer contains a compound represented by the following general formula (I) as a coloring / decoloring control agent, the reversible thermosensitive recording layer has excellent thermal response and can cope with high-speed erasing, and furthermore has a stable storage property. It has been found that a reversible thermosensitive recording medium having high resilience (particularly heat storage characteristics) is provided.

[0012]

Embedded image In the formula (I), n represents an integer of 2 to 4, and R ₁ represents a bond or a hydrocarbon group having 1 to 6 carbon atoms. Similarly, R ₂ represents a hydrocarbon group having 1 to 20 carbon atoms.
Further, X represents a divalent group containing a hetero atom. However, a plurality of R ₁ , R ₂ and X generated by n may be different.

Hereinafter, the reversible thermosensitive recording medium of the present invention will be described in detail. In the compound of the formula (I) contained in the reversible thermosensitive recording medium of the present invention, R ₁ and R ₂ represent a hydrocarbon group which may have a substituent, and these may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. It may be a hydrocarbon group or a hydrocarbon group composed of both. Further, the aliphatic hydrocarbon group may be linear or branched, and may have an unsaturated bond. Examples of the substituent attached to the hydrocarbon group include a hydroxyl group, a halogen, and an alkoxy group. Further, when the carbon number of R ₂ is 8 or more, the effect on the erasability is large, and it is more preferable that the carbon number is 11 or more. Preferred examples of R ₁ include the following in addition to a bond.

[0014]

[Table 1]

Preferred examples of R ₂ include the following.

[0016]

[Table 2]

In the formula, q, q ', q "and q'" each represent an integer satisfying the carbon number of R ₁ and R ₂ . X represents a divalent group containing a hetero atom, and is preferably

[0018]

[Table 3] Represents a divalent group having at least one group represented by Examples include the following.

[0019]

[Table 4]

The structure of the decoloring accelerator used in the present invention is shown below.

[0021]

[Table 5]

The above R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ represent R
Represents the same group as ₁ , but may be different from each other. R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ represent the same groups as R _2, which may be different from each other, and X ₁ , X ₂ , X
₃ and X ₄ represent the same groups as X, which may be different from each other. In the reversible thermosensitive recording medium of the present invention, when n is 2, the erasability is particularly excellent. Of these, compounds having the structures shown below are particularly preferred.

[0023]

Embedded image

Specific examples of this compound include the compounds shown in Table 6. Other compounds can be represented by the same groups. The present invention is not limited to these.

[0025]

[Table 6-1]

[0026]

[Table 6-2]

The use of the compound represented by the following general formula (A) as a coloring / decoloring control agent used in the present invention provides excellent storage characteristics and high-speed erasing characteristics. Examples of the coloring / decoloring controlling agent include a structure represented by the following formula.

[0028]

Embedded imageWhere X₁₁, X₁₂And X₁₃Represents a group containing a hetero atom
And R₃₁, R₃₂And R₃₃Is a group having 1 to 22 carbon atoms
Express. Also, j, l and m are each independently 0 or
Represents 1 and k represents an integer of 0 to 4. Where j,
k, l and m are never 0 at the same time. further,
R repeated when k is 2 or more₃₃And X₁₂Are the same
May be different. Also, R₃₁, R₃₂, R₃₃
And R ₃₄May contain a heterocyclic ring. More preferred
Is R₃₁, R₃₂And R₃₃Has a sum of 8 or more carbon atoms
Is preferred. R₃₁, R₃₂And R₃₃Has a substituent
Which may be an aliphatic hydrocarbon.
May be an aromatic group or an aromatic hydrocarbon group.
And a hydrocarbon group composed of the two. Also aliphatic carbonization
Hydrogen groups may be straight or branched and have an unsaturated bond.
It may be. As a substituent attached to the hydrocarbon group, water
There are an acid group, a halogen, an alkoxy group and the like. Also, R₃₁,
R₃₂, R₃₃And R₃₄If the sum of the carbon number of
The number of carbon atoms is preferably 8 or more because the stability and the decoloration property are reduced.
And more preferably 11 or more. R₃₁, R₃₃
Preferred examples include the following.

[0029]

[Table 7]

Preferred examples of R ₃₂ , R ₃₃ and R ₃₄ include the following.

[0031]

[Table 8]

In the formula, q, q ', q "and q'" each represent an integer satisfying the number of carbon atoms of R ₃₁ , R ₃₂ and R ₃₃ . Further, when X ₁₁ and X ₁₃ are at the terminal position of the structural formula as examples, preferably

[0033]

[Table 9] Represents a group having at least one group represented by Examples include the following.

[0034]

[Table 10]

X ₁₁ and X ₁₂ each represent a divalent group containing a hetero atom.

[0036]

[Table 11] Represents a divalent group having at least one group represented by Examples include the following.

[0037]

[Table 12]

The preferred structures of the coloring and decoloring control agents used in the present invention are illustrated below, but the present invention is not limited to these compounds.

[0039]

Embedded image

[0040]

Embedded image

[0041]

Embedded image

The above R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ , X ₁₁ , X
₁₂ and X ₁₃ each represent the same group as described above. N is an integer of 0 to 4, and R ₃₃ and X ₁₂ repeated when k _{1 to} k ₃ are 2 or more may be the same or different. Further, l ₁ represents 0 or 1. However, k _{1 to} k ₃ and l ₁ are never 0 at the same time. Further, particularly preferred structures include the following.

[0043]

Embedded image

[0044]

Embedded image

[0045]

Embedded image

[0046]

Embedded image

[0047]

Embedded image

[0048]

Embedded image

Specific examples of the coloring and decoloring controlling agents used in the present invention include, for example, those of the formula (h) shown in Table 1 below.
3 compounds. Similar compounds are also used for formula (i).

[0050]

[Table 13]

As a more specific example, for example,

[0052]

Embedded image and

[0053]

Embedded image Examples of the compound represented by are compounds shown in Table 14.

[0054]

[Table 14]

Further, the deterioration due to repeated use of the recording medium, that is, the destruction of the coating film due to a large number of printing / erasing operations is greatest in the recording layer. Found to improve.

Further, in the reversible thermosensitive recording medium of the present invention, the reversible thermosensitive recording layer contains a resin in a crosslinked state, whereby the heat resistance of the recording layer is improved and the repetitive durability is improved. The durability can be further improved by providing a protective layer mainly composed of the crosslinked resin on the recording layer containing the crosslinked resin.

The resin in a cross-linked state is, for example, a combination of a cross-linking agent and a resin having an active group which reacts with the cross-linking agent, and is a resin which can be cross-linked and cured by heat.
The resins used here include, for example, phenoxy resin, polyvinyl butyral resin, cellulose acetate propionate, cellulose acetate butyrate, and the like, a resin having a group that reacts with a crosslinking agent such as a hydroxyl group, a carboxyl group, or a hydroxyl group, a carboxyl group, and the like There is a resin in which a monomer is copolymerized with another monomer. Copolymer resins include, for example, PVC-based, acrylic-based, styrene-based resins, and specifically, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-hydroxypropyl acrylate copolymer, Vinyl chloride
Examples thereof include a vinyl acetate-maleic anhydride copolymer.

Examples of the crosslinking agent for thermal crosslinking include isocyanates, amino resins, phenol resins, amines, epoxy compounds and the like. For example, the isocyanates are isocyanate compounds having a plurality of isocyanate groups, specifically, hexamethylene diisocyanate (HDI), toluene diisocyanate (TD
I), xylylene diisocyanate (XDI) and the like, and adduct type, buret type, isocyanurate type and blocked isocyanates thereof with trimethylolpropane and the like. The amount of the crosslinking agent to be added to the resin is preferably such that the ratio of the functional group of the crosslinking agent to the number of active groups contained in the resin is 0.01 to 1, and below this, the thermal strength is insufficient, and more than this. When added, it has an adverse effect on color development / decoloration characteristics. Still further, a catalyst used in this type of reaction may be used as a crosslinking accelerator. Examples of the crosslinking accelerator include, for example, 1,4
Tertiary amines such as -diaza-bicyclo [2,2,2] octane; and metal compounds such as organic tin compounds.

Next, examples of monomers used for curing with an electron beam and ultraviolet rays include the following. Examples of monofunctional monomers Methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, Cyclohexyl methacrylate, benzyl methacrylate, methacrylic acid, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl methacrylate methyl chloride salt, diethylaminoethyl methacrylate, glycidyl methacrylate, methacrylic acid Acid tetrahydrofurfuryl, allyl methacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene dimethacrylate Glycol, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane trimethacrylate, methacrylic acid 2-
Ethoxyethyl, 2-ethylhexyl acrylate, 2
-Ethoxyethyl acrylate, 2-ethoxyethoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, dicyclopentenylethyl acrylate, N-vinylpyrrolidone,
Vinyl acetate and the like.

Examples of difunctional monomers 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, tripropylene Glycol diacrylate, polypropylene glycol diacrylate, bisphenol A ethylene oxide adduct diacrylate, glycerin methacrylate acrylate, diacrylate of neopentyl glycol 2 mol propylene oxide adduct, diethylene glycol diacrylate, polyethylene glycol (400) diacrylate, hydroxypivalin Diacrylate of ester of acid and neopentyl glycol,
2,2-bis (4-acryloxydiethoxyphenyl)
Propane, diacrylate of neopentyl glycol diadipate, diacrylate of ε-caprolactone adduct of neopentyl glycol hydroxypivalate, 2
-(2-hydroxy-1,1-dimethylethyl) -5-
Hydroxymethyl-5-ethyl-1,3-dioxane diacrylate, tricyclodecane dimethylol diacrylate, ε-caprolactone adduct of tricyclodecane dimethylol diacrylate, diacrylate of glycidyl ether of 1,6-hexanediol, etc. .

Examples of polyfunctional monomers: Trimethylolpropane triacrylate, glycerin propylene oxide addition acrylate, trisacryloyloxyethyl phosphate, pentaerythritol acrylate, triacrylate of 3 moles of propylene oxide adduct of trimethylolpropane, dipentaerythritol. Polyacrylate, polyacrylate of caprolactone adduct of dipentaerythritol,
Dipentaerythritol triacrylate propionate, hydroxypivalaldehyde-modified dimethylolpropane triacrylate, tetraacrylate dipentaerythritol propionate, ditrimethylolpropane tetraacrylate, pentaacrylate dipentaerythritol propionate, dipentaerythritol hexaacrylate, dipentaerythritol Ε-caprolactone adduct of pentaerythritol hexaacrylate and the like.

Examples of oligomers Bisphenol A-diepoxyacrylic acid adducts and the like.

When crosslinking is carried out using ultraviolet rays, the following photopolymerization initiator and photopolymerization accelerator are used. Examples of the photopolymerization initiator include benzoin ethers such as isobutyl benzoin ether, isopropyl benzoin ether, benzoin ethyl ether, and benzoin methyl ether. 1-phenyl-1,2-propanedione-
Α-acyloxime esters such as 2- (o-ethoxycarbonyl) oxime. Benzyl ketals such as 2,2-dimethoxy-2-phenylacetophenone, benzyl and hydroxycyclohexyl phenol ketone. Acetophenone dielectrics such as diethoxyacetophenone and 2-hydroxy-2-methyl-1-phenylpropan-1-one; Benzophenone, 1-chlorothioxanthone, 2-chlorothioxanthone, isopropylthioxanthone, 2-methylthioxanthone, 2-methylthioxanthone, 2-
Ketones such as chlorobenzophenone are exemplified. These photopolymerization initiators are used alone or in combination of two or more. The addition amount is preferably from 0.005 to 1.0 part by weight, more preferably from 0.01 to 0.5 part by weight, based on 1 part by weight of the crosslinking agent.

As the photopolymerization accelerator, there are aromatic tertiary amines and aliphatic amines. Specific examples include p-dimethylaminobenzoic acid isoamyl ester and p-dimethylaminobenzoic acid ethyl ester. These photopolymerization accelerators are used alone or in combination of two or more. The amount of addition is 0.1 to 1 part by weight of photopolymerization initiator.
It is preferably 1 to 5 parts by weight, more preferably 0.3 to 3 parts by weight.

As a light source for ultraviolet irradiation used in the present invention, there are a mercury lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, a flash lamp, etc., and the ultraviolet absorption wavelength of the above-mentioned photopolymerization initiator and photopolymerization accelerator. A light source having an emission spectrum corresponding to the above may be used. As the UV irradiation conditions, the lamp output and the transport speed may be determined according to the irradiation energy required for crosslinking the resin. In addition, as the electron beam irradiation device, scanning type, depending on the purpose of irradiation area, irradiation dose, etc.,
Any of the non-scanning types may be selected, and the irradiation conditions are electron flow, irradiation width, and irradiation width depending on the dose required to crosslink the resin.
The transport speed may be determined.

Further, according to the present invention, the use of a phenolic compound represented by the following formula as a color developer can provide a good image contrast.

[0067]

Embedded image In the formula, X ₄ represents a divalent group containing a hetero atom or a direct bond, and X ₅ represents a divalent group containing a hetero atom. R
₅₀ represents a divalent hydrocarbon group, and R ₅₁ represents a group having 1 to 2 carbon atoms.
2 represents a hydrocarbon group. Also, v represents an integer of 0 to 4, and R ₅₀ and X repeated when v is 2 to 4
₅ may be the same or different. U represents 1 to 3.

Specifically, R ₅₀ and R ₅₁ represent a hydrocarbon group which may have a substituent, which may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, or both of them. Or a hydrocarbon group composed of Further, the aliphatic hydrocarbon group may be linear or branched, and may have an unsaturated bond. As a substituent attached to the hydrocarbon group,
There are a hydroxyl group, a halogen, an alkoxy group and the like. Note that R ₅₀
May be a direct bond. When the sum of the number of carbon atoms of R ₅₀ and R ₅₁ is 7 or less, the stability of color development and the decoloring property decrease, so that the number of carbon atoms is preferably 8 or more, more preferably 11 or more. Preferred examples of R ₅₀ include the following in addition to the direct bond.

[0069]

[Table 15]

Preferred examples of R ₅₁ include the following.

[0071]

[Table 16]

In the formula, q, q ', q "and q'" each represent an integer satisfying the carbon number of R ₅₀ and R ₅₁ .
X ₄ and X ₅ each represent a divalent group containing a hetero atom,

[0073]

[Table 17] Represents a divalent group having at least one group represented by Examples include the following.

[0074]

[Table 18]

Particularly preferred examples of the phenol compound used in the present invention include a compound represented by the following formula.

[0076]

Embedded image

[0077]

Embedded image

[0078]

Embedded image

[0079]

Embedded image

[0080]

Embedded image

[0081]

Embedded image

[0082]

Embedded image

[0083]

Embedded image In the formula, w, w ′ and y each independently represent an integer satisfying the number of carbon atoms of R ₅₀ or R ₅₁ .

More specific examples of the phenol compound in the present invention include, for example, compounds shown in Table 19 below as an example of Chemical formula 20. In addition, the compounds represented by the above-mentioned other chemical formulas 19 and 21 to 26 are also exemplified as the same compounds. But,
The present invention is not limited to these.

[0085]

[Table 19-1]

[0086]

[Table 19-2]

[0087]

[Table 19-3]

Further, more specific phenol compounds include, for example, the following. Specific examples of compounds represented by the following formula in Table 19 are shown in Table 2 as examples.
Listed as 0. The same applies to the compounds represented by other formulas in Table 19. However, the present invention is not limited to these.

[0089]

Embedded image

[0090]

[Table 20]

Further, according to the present invention, a protective layer using a cross-linked resin may be provided on the recording layer, and the cross-linked resin may be the above-mentioned thermosetting resin, ultraviolet curable resin, or the like. An electronic curable resin or the like is used. Thereby, the head matching property at the time of printing is improved, and the repetition durability is further improved. Further, additives such as an ultraviolet absorber, an inorganic or / and organic filler, and a lubricant can be contained in the protective layer.

In the present invention, another developer can be used in combination with the phenolic compound. As a color developing agent to be used in combination, as disclosed in Japanese Patent Application Laid-Open No. 5-124360 together with typical examples of a phosphoric acid compound having a long-chain hydrocarbon group and a fatty acid compound phenol compound, a coloring agent is present in the molecule. A compound having both a structure capable of developing color and a structure controlling the cohesion between molecules can be used in combination.

The following compounds can be exemplified as the color developer used in the present invention. Examples of the organic phosphoric acid developer include the following compounds. Dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, docosylphosphonic acid, tetracosylphosphonic acid,
Ditetradecyl phosphate, dihexadecyl phosphate, dioctadecyl phosphate, dieicosyl phosphate, dibehenyl phosphate and the like.

As the aliphatic carboxylic compound, the following compounds can be exemplified. 2-hydroxytetradecanoic acid, 2-hydroxyhexadecanoic acid, 2-hydroxyoctadecanoic acid, 2-hydroxyeicosanoic acid, 2-hydroxydocosanoic acid, 2-bromohexadecanoic acid, 2-bromooctadecanoic acid, 2-bromoeicosanoic acid 2-bromodocosanoic acid, 3-bromooctadecanoic acid, 3-bromodocosanoic acid, 2,3-dibromooctadecanoic acid,
Fluorododecanoic acid, 2-fluorotetradecanoic acid, 2
-Fluorohexadecanoic acid, 2-fluorooctadecanoic acid, 2-fluoroeicosanoic acid, 2-fluorodocosanoic acid, 2-iodohexadecanoic acid, 2-iodooctadecanoic acid, 3-iodohexadecanoic acid, 3-iodooctadecanoic acid, par Fluorooctadecanoic acid and the like.

Examples of the aliphatic dicarboxylic acid and tricarboxylic acid compounds include the following compounds. 2-
Dodecyloxysuccinic acid, 2-tetradecyloxysuccinic acid, 2-hexadecyloxysuccinic acid, 2-octadecyloxysuccinic acid, 2-eicosyloxysuccinic acid,
2-dodecyloxysuccinic acid, 2-dodecylthiosuccinic acid, 2-tetradecylthiosuccinic acid, 2-hexadecylthiosuccinic acid, 2-octadecylthiosuccinic acid, 2-eicosylthiosuccinic acid, 2-docosylthiosuccinic acid, 2
-Tetracosylthiosuccinic acid, 2-hexadecyldithiosuccinic acid, 2-octadecyldithiosuccinic acid, 2-eicosyldithiosuccinic acid, dodecylsuccinic acid, tetradecylsuccinic acid, pentadecylsuccinic acid, hexadecylsuccinic acid, octadecylsuccinic acid, eicosylsuccinic Acid, docosyl succinic acid, 2,3-dihexadecyl succinic acid,
2,3-dioctadecylsuccinic acid, 2-methyl-3-hexadecylsuccinic acid, 2-methyl-3-octadecylsuccinic acid, 2-octadecyl-3-hexadecylsuccinic acid, hexadecylmalonic acid, octadecylmalonic acid, eicosyl Malonic acid, docosylmalonic acid, dihexadecylmalonic acid, dioctadecylmalonic acid, didocosylmalonic acid, methyloctadecylmalonic acid, 2-hexadecylglutaric acid, 2-octadecylglutaric acid, 2-eicosylglutaric acid, docosylglutaric acid, 2-pentadecyl adipic acid, 2-octadecyl adipic acid, 2-eicosyl adipic acid, 2-docosyl adipic acid, 2-hexadecanoyloxypropane-1,2,3-tricarboxylic acid, 2-octadecanoyloxy Propane-1,2,3
-Tricarboxylic acids and the like.

As the leuco dye, conventionally known leuco dyes can be arbitrarily used, and the following compounds are particularly preferably used alone or in combination.

[0097]

Embedded image (Wherein, R ₆₂ and R ₆₃ represent a lower alkyl group, an aryl group which may be substituted, or a hydrogen atom, and R ₆₂ and R ₆₃ may be bonded to each other to form a ring. R ₆₄ is a lower alkyl group) group, a halogen atom or a hydrogen atom, also, R ₆₅
Represents a lower alkyl, a halogen atom, a hydrogen atom or a substituted anilino group represented by the following formula. ) Or R _{62 to} R ₆₅
Independently

[0098]

Embedded image Represents a group. (In the formula, R ₆₆ represents a lower alkyl group or a hydrogen atom, Y represents a lower alkyl group or a halogen atom, and z represents an integer of 0 to 3.)

[0099]

Embedded image (In the formula, R ₆₇ to R ₇₀ represent an alkyl group or a hydrogen atom, and R ₇₁ represents an alkyl group, an alkoxyl group, or a hydrogen atom.)

[0100]

Embedded image (In the formula, R ₇₂ to R ₇₅ represent a lower alkyl group or a hydrogen atom, and R ₇₆ and R ₇₇ represent an alkyl group, an alkoxyl group, or a hydrogen atom.)

Examples of the leuco dye used in the present invention are described below, but the present invention is not limited to these. 2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-di (n-butylamino) fluoran, 2-anilino-3-methyl-
6- (Nn-propyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N-isopropyl-N-methylamino) fluoran, 2-anilino-3
-Methyl-6- (N-isobutyl-N-methylamino)
Fluoran, 2-anilino-3-methyl-6- (Nn
-Amyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N-sec-butyl-N-methylamino) fluoran, 2-anilino-3-methyl-6
-(Nn-amyl-N-ethylamino) fluoran,
2-anilino-3-methyl-6- (N-iso-amyl-N-ethylamino) fluoran, 2-anilino-3-
Methyl-6- (NN-propyl-N-isopropylamino) fluoran, 2-anilino-3-methyl-6
(N-cyclohexyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N-ethyl-p
-Toluidino) fluoran, 2-anilino-3-methyl-6- (N-methyl-p-toluidino) fluoran, 2
-(M-trichloromethylanilino) -3-methyl-6
-Diethylaminofluoran, 2- (m-trifluoromethylanilino) -3-methyl-6-diethylaminofluoran, 2- (m-trichloromethylanilino) -3-
Methyl-6- (N-cyclohexyl-N-methylamino) fluoran, 2- (2,4-dimethylanilino)-
3-methyl-6-diethylaminofluoran, 2- (N
-Ethyl-p-toluidino) -3-methyl-6- (N-
Ethylanilino) fluoran, 2- (N-ethyl-p-
Toluidino) -3-methyl-6- (N-propyl-p-
Toluidino) fluoran, 2-anilino-6- (N-n
-Hexyl-N-ethylamino) fluoran, 2- (o
-Chloroanilino) -6-diethylaminofluoran,
2- (o-chloroanilino) -6-dibutylaminofluoran, 2- (m-trifluoromethylanilino) -6
Diethylaminofluorane, 2,3-dimethyl-6-dimethylaminofluoran, 3-methyl-6- (N-ethyl-p-toluidino) fluoran, 2-chloro-6-diethylaminofluoran, 2-bromo-6- Diethylaminofluorane, 2-chloro-6-dipropylaminofluoran, 3-chloro-6-cyclohexylaminofluoran, 3-bromo-6-cyclohexylaminofluoran, 2-chloro-6- (N-ethyl-N -Isoamylamino) fluoran, 2-chloro-3-methyl-6-diethylaminofluoran, 2-anilino-3-chloro-
6-diethylaminofluoran, 2- (o-chloroanilino) -3-chloro-6-cyclohexylaminofluoran, 2- (m-trifluoromethylanilino) -3-chloro-6-diethylaminofluoran, 2- ( 2,3-
Dichloroanilino) -3-chloro-6-diethylaminofluoran, 1,2-benzo-6-diethylaminofluoran, 3-diethylamino-6- (m-trifluoromethylanilino) fluoran, 3- (1-ethyl -2-methylindol-3-yl) -3- (2-ethoxy-4
-Diethylaminophenyl) -4-azaphthalide, 3-
(1-ethyl-2-methylindol-3-yl) -3
-(2-ethoxy-4-diethylaminophenyl) -7
-Azaphthalide, 3- (1-octyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3 -Yl) -3- (2-
Methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3-
Yl) -3- (2-methyl-4-diethylaminophenyl) -7-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2
-Methylindol-3-yl) -3- (4-N-n-
Amyl-N-methylaminophenyl) -4-azaphthalide, 3- (1-methyl-2-methylindol-3-yl) -3- (2-hexyloxy-4-diethylaminophenyl) -4-azaphthalide, 3, 3-bis (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3,3-bis (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide.

As the color former used in the present invention, in addition to the above-mentioned fluoran compounds and azaphthalide compounds, conventionally known leuco dyes can be used alone or in combination. The coloring agent is shown below. 2- (p-acetylanilino)-
6- (Nn-amyl-Nn-butylamino) fluoran, 2-benzylamino-6- (N-ethyl-p-toluidino) fluoran, 2-benzylamino-6- (N
-Methyl-2,4-dimethylanilino) fluoran, 2
-Benzylamino-6- (N-ethyl-2,4-dimethylanilino) fluoran, 2-benzylamino-6-
(N-methyl-p-toluidino) fluoran, 2-benzylamino-6- (N-ethyl-p-toluidino) fluoran, 2- (di-p-methylbenzylamino) -6
(N-ethyl-p-toluidino) fluoran, 2- (α
-Phenylethylamino) -6- (N-ethyl-p-toluidino) fluoran, 2-methylamino-6- (N-
Methylanilino) fluoran, 2-methylamino-6-
(N-ethylanilino) fluoran, 2-methylamino-6- (N-propylanilino) fluoran, 2-ethylamino-6- (N-methyl-p-toluidino) fluoran, 2-methylamino-6- (N -Methyl-2,4-
Dimethylanilino) fluoran, 2-ethylamino-6
-(N-ethyl-2,4-dimethylanilino) fluoran, 2-dimethylamino-6- (N-methylanilino)
Fluoran, 2-dimethylamino-6- (N-ethylanilino) fluoran, 2-diethylamino-6- (N-
Methyl-p-toluidino) fluoran, 2-diethylamino-6- (N-ethyl-p-toluidino) fluoran, 2-dipropylamino-6- (N-methylanilino) fluoran, 2-dipropylamino-6- (N -Ethylanilino) fluoran, 2-amino-6- (N-methylanilino) fluoran, 2-amino-6- (N-ethylanilino) fluoran, 2-amino-6- (N-propylanilino) fluoran, 2-amino- 6- (N-
Methyl-p-toluidino) fluoran, 2-amino-6
-(N-ethyl-p-toluidino) fluoran, 2-amino-6- (N-propyl-p-toluidino) fluoran, 2-amino-6- (N-methyl-p-ethylanilino) fluoran, 2-amino- 6- (N-ethyl-p-
Ethylanilino) fluoran, 2-amino-6- (N-
Propyl-p-ethylanilino) fluoran, 2-amino-6- (N-methyl-2,4-dimethylanilino) fluoran, 2-amino-6- (N-ethyl-2,4-dimethylanilino) fluoran, 2-amino-6- (N-
Propyl-2,4-dimethylanilino) fluoran, 2
-Amino-6- (N-methyl-p-chloroanilino) fluoran, 2-amino-6- (N-ethyl-p-chloroanilino) fluoran, 2-amino-6- (N-propyl-p-chloroanilino) fluoran, 1,2-benzo-6- (N-ethyl-N-isoamylamino) fluoran, 1,2-benzo-6-dibutylaminofluoran,
1,2-benzo-6- (N-methyl-N-cyclohexylamino) fluoran, 1,2-benzo-6- (N-ethyl-N-toluidino) fluoran, and others.

Specific examples of other color formers preferably used in the present invention are as follows. 2-anilino-3-methyl-6- (N-2-ethoxypropyl-N-
Ethylamino) fluoran, 2- (p-chloroanilino) -6- (Nn-octylamino) fluoran, 2
-(P-chloroanilino) -6- (Nn-palmitylamino) fluoran, 2- (p-chloroanilino) -6
-(Di-n-octylamino) fluoran, 2-benzoylamino-6- (N-ethyl-p-toluidino) fluoran, 2- (o-methoxybenzoylamino) -6
(N-methyl-p-toluidino) fluoran, 2-dibenzylamino-4-methyl-6-diethylaminofluoran, 2-dibenzylamino-4-methoxy-6- (N
-Methyl-p-toluidino) fluoran, 2-dibenzylamino-4-methyl-6- (N-ethyl-p-toluidino) fluoran, 2- (α-phenylethylamino)
-4-methyl-6-diethylaminofluoran, 2-
(P-Toluidino) -3- (t-butyl) -6- (N-
Methyl-p-toluidino) fluoran, 2- (o-methoxycarbonylamino) -6-diethylaminofluoran, 2-acetylamino-6- (N-methyl-p-toluidino) fluoran, 4-methoxy-6- (N -Ethyl-p-toluidino) fluoran, 2-ethoxyethylamino-3-chloro-6-dibutylaminofluoran, 2
-Dibenzylamino-4-chloro-6- (N-ethyl-
p-Toluidino) fluoran, 2- (α-phenylethylamino) -4-chloro-6-diethylaminofluoran, 2- (N-benzyl-p-trifluoromethylanilino) -4-chloro-6-diethylaminofluor Oran, 2
-Anilino-3-methyl-6-pyrrolidinofluoran,
2-anilino-3-chloro-6-pyrrolidinofluoran, 2-anilino-3-methyl-6- (N-ethyl-N
-Tetrahydrofurfurylamino) fluoran, 2-mesidino-4 ', 5'-benzo-6-diethylaminofluoran, 2- (m-trifluoromethylanilino) -3-
Methyl-6-pyrrolidinofluoran, 2- (α-naphthylamino) -3,4benzo-4′-bromo-6- (N-
Benzyl-N-cyclohexylamino) fluoran, 2
-Piperidino-6-diethylaminofluoran, 2-
(Nn-propyl-p-trifluoromethylanilino)
-6-morpholinofluoran, 2- (di-N-p-chlorophenyl-methylamino) -6-pyrrolidinofluoran, 2- (Nn-propyl-m-trifluoromethylanilino) -6 Morpholinofluoran, 1,2-benzo-6- (N-ethyl-NN-octylamino) fluoran, 1,2-benzo-6-diallylaminofluoran, 1,2-benzo-6- (N -Ethoxyethyl-N
-Ethylamino) fluoran, benzoleucomethylene blue, 2- [3,6-bis (diethylamino) -7-
(O-chloroanilino) xanthyl] lactam benzoate, 2- [3,6- (diethylamino) -9- (o-chloroanilino) xanthyl] benzoate lactam, 3,3
-Bis (p-dimethylaminophenyl) -phthalide,
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis- (p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3- Screw-
(P-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis- (p-dibutylaminophenyl) phthalide, 3- (2-methoxy-4-dimethylaminophenyl) -3- (2-hydroxy-4, 5- (dichlorophenyl) phthalide, 3- (2-hydroxy-4-dimethylaminophenyl) -3- (2-methoxy-5-chlorophenyl) phthalide, 3- (2-hydroxy-4-dimethoxyaminophenyl) -3- ( 2-methoxy-5-chlorophenyl) phthalide, 3- (2-hydroxy-4-dimethylaminophenyl) -3- (2-methoxy-5-nitrophenyl) phthalide, 3- (2-hydroxy-4-)
Diethylaminophenyl) -3- (2-methoxy-5-
Methylphenyl) phthalide, 3- (2-methoxy-4-
Dimethylaminophenyl) -3- (2-hydroxy-4
-Chloro-5-methoxyphenyl) phthalide, 3,6-
Bis (dimethylamino) fluorenespiro (9,3 ')
-6'-dimethylaminophthalide, 6'-chloro-8 '
-Methoxy-benzoindolino-spiropyran, 6'-
Bromo-2'-methoxy-benzoindolino-spiropyran, and others.

The reversible thermosensitive recording medium of the present invention can form a relatively colored state and a decolored state depending on the heating temperature and / or the cooling rate after heating. The basic coloring / decoloring phenomenon of the composition comprising the color former and the developer used in the present invention will be described. FIG. 1 shows the relationship between the color density and the temperature of the recording medium. Introduction gradually heated the recording medium in the decolored state (A), a molten colored state occurs coloration at temperatures T ₁ begins to melt (B). When the color is rapidly cooled from the melted color development state (B), the temperature can be lowered to room temperature while maintaining the color development state, and a solid color development state (C) is obtained. Whether or not this color-developed state is obtained depends on the rate of temperature decrease from the molten state. In the case of slow cooling, decoloration occurs in the process of temperature decrease, and the same decolored state (A) or quenched color state (C) as at the beginning. A) is formed with a relatively lower concentration. On the other hand, rapidly cooled colored state (C) is again raised gradually and decoloration occurs with a color temperature lower than temperature T ₂ and (E from D), the same colorless state, including when the temperature decreases from which (A)
Return to The actual color development temperature and decolorization temperature can be selected according to the purpose because they vary depending on the combination of the color developer and color developer used. Further, the density in the molten color development state and the color development density after quenching are not always the same, and may differ.

In the recording medium of the present invention, the color-developed state (C) obtained by quenching from the molten state is a state in which the developer and the color-developing agent are mixed in such a manner that they can react with each other between molecules. It often forms a state. This state is a state in which the color developer and the color forming agent aggregate to maintain the color development, and it is considered that the color formation is stabilized by the formation of the aggregate structure. On the other hand, the decolored state is a state where both are phase-separated. This state is a state in which molecules of at least one compound are aggregated to form a domain or crystallized, and it is considered that the color former and the developer are separated and stabilized by aggregation or crystallization. Can be In the present invention, in many cases,
More complete decoloring occurs due to phase separation of the two and crystallization of the developer. In the decoloring by slow cooling from the molten state and the decoloring by raising the temperature from the colored state shown in FIG. 1, the cohesive structure changes at this temperature, and phase separation and crystallization of the developer occur.

The formation of color recording on the reversible thermosensitive recording medium of the present invention may be performed by heating the mixture to a temperature at which it is melted and mixed by a thermal head or the like, and then rapidly cooling the mixture. The decoloring is performed by two methods: a method of gradually cooling from a heating state and a method of heating to a temperature slightly lower than a coloring temperature. However, they are the same in the sense that they both phase-separate or temporarily hold at a temperature at which at least one crystallizes. The rapid cooling in the formation of a color-developed state is for preventing the phase separation temperature or the crystallization temperature from being maintained. Here, the rapid cooling and the slow cooling are relative to one composition, and the boundary varies depending on the combination of the color former and the developer.

The appropriate range of the ratio of the color former to the color developer varies depending on the combination of the compounds used, but the developer is generally in the range of 0.1 to 20 with respect to the color developer 1 in a molar ratio. Preferably it is in the range of 0.2 to 10. If the amount of the developer is smaller or larger than this range, the density of the color-developed state is reduced, which is problematic. Further, the ratio of the decoloring accelerator and the coloring / decoloring control agent is preferably from 0.1% by weight to 300% by weight, more preferably from 3% by weight to 100% by weight, based on the developer. Further, the color former and the developer can be used by being encapsulated in microcapsules.

The ratio of the color-forming component and the resin in the recording layer is preferably from 0.1 to 10 with respect to the color-forming component 1. If the ratio is less than this, the thermal strength of the recording layer is insufficient. Is a problem.

The recording layer is formed by uniformly mixing and dispersing the above-mentioned mixture of the color developer, the color former, the color erasure accelerator, the color elimination control agent, the crosslinked resin and the coating solution solvent. Use the prepared coating liquid. Specific examples of the solvent used for preparing the coating liquid include water; methanol, ethanol,
Alcohols such as isopropanol, n-butanol and methyl isocarbinol; acetone, 2-butanone,
Ketones such as ethyl amyl ketone, diacetone alcohol, isophorone and cyclohexanone; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; diethyl ether, isopropyl ether;
Ethers such as tetrahydrofuran, 1,4-dioxane, 3,4-dihydro-2H-pyran; glycol ethers such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol and ethylene glycol dimethyl ether; 2-methoxyethyl Glycol ether acetates such as acetate, 2-ethoxyethyl acetate, and 2-butoxyethyl acetate;
Esters such as methyl acetate, ethyl acetate, isobutyl acetate, amyl acetate, ethyl lactate and ethylene carbonate; aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as hexane, heptane, iso-octane and cyclohexane And methylene chloride, 1,
Halogenated hydrocarbons such as 2-dichloroethane, dichloropropane, and chlorobenzene; sulfoxides such as dimethyl sulfoxide; N-methyl-2-pyrrolidone;
Examples thereof include pyrrolidones such as N-octyl-2-pyrrolidone.

The coating liquid can be prepared using a known coating liquid dispersing apparatus such as a paint shaker, a ball mill, an attritor, a three-roll mill, a Keddy mill, a sand mill, a dyno mill, and a colloid mill. In addition, each material may be dispersed in a solvent using the above-mentioned coating liquid dispersion apparatus, or each material may be dispersed alone in the solvent and mixed. Further, it may be heated and melted and precipitated by rapid cooling or slow cooling.

The coating method for providing the recording layer is not particularly limited, and may be blade coating, wire bar coating, spray coating, air knife coating, bead coating, curtain coating, gravure coating, kiss coating, Known methods such as reverse roll coating, dip coating, and die coating can be used.

The method for drying and curing the recording layer is as follows:
A hardening treatment is performed if necessary. As long as it can be crosslinked by heat, the heat treatment may be performed at a relatively high temperature for a short time using a high-temperature bath or the like, or the heat treatment may be performed at a relatively low temperature for a long time. Also,
Known curing devices may be used for ultraviolet curing and electron beam curing. For example, as a light source at the time of ultraviolet irradiation, there are a mercury lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, a flash lamp, etc., and an emission spectrum corresponding to the ultraviolet absorption wavelength of the photopolymerization initiator and the photopolymerization accelerator described above. May be used. As the UV irradiation conditions, the lamp output and the transport speed may be determined according to the irradiation energy required for crosslinking the resin. Further, as the electron beam irradiation device, any of a scanning type and a non-scanning type may be selected according to the purpose such as an irradiation area and an irradiation dose, and the irradiation condition may be selected according to a dose required for crosslinking the resin. The flow, irradiation width, and transport speed may be determined.

The thickness of the recording layer is preferably in the range of 1 to 20 μm, more preferably 3 to 10 μm.

The support of the reversible thermosensitive recording medium of the present invention is paper, resin film, synthetic paper, metal foil, glass or a composite thereof, and may be any as long as it can hold the recording layer.

In the reversible thermosensitive recording medium of the present invention, an additive for improving or controlling the coating characteristics and the coloring and decoloring characteristics of the recording layer can be used as necessary. These additives include, for example, surfactants, conductive agents, fillers, antioxidants, light stabilizers, color stabilizers, and the like.

The reversible thermosensitive recording medium of the present invention basically comprises a support provided with a recording layer containing the above-mentioned crosslinked resin and, if necessary, a protective layer containing the crosslinked resin. However, in order to improve the characteristics as a recording medium, an adhesive layer, an intermediate layer, an undercoat layer, a back coat layer, and the like can be provided. Further, a magnetic recording layer may be provided. Further, each of the above-mentioned layers and the support may be colored with a coloring agent. In this case, a part or the whole surface of the recording medium may be colored, for example, by printing. Further, a colorless or light-colored print protection layer containing a resin as a main component may be provided on the colored print layer.

Examples of the resin used for the protective layer include polyvinyl alcohol, styrene-maleic anhydride copolymer, carboxy-modified polyethylene, melamine-formaldehyde resin, and urea-formaldehyde resin in addition to the above-mentioned resin in a crosslinked state. The thickness of the protective layer is 0.1
The range is preferably from 20 to 20 μm, more preferably from 0.3 to
10 μm.

An intermediate layer is provided between the recording layer and the protective layer for the purpose of improving the adhesion between the recording layer and the protective layer, preventing deterioration of the recording layer due to coating of the protective layer, and preventing transfer of additives in the protective layer to the recording layer. It is also preferred. In addition, a heat insulating undercoat layer can be provided between the support and the recording layer in order to effectively use the applied heat. The heat insulating layer can be formed by applying organic or inorganic fine hollow particles using a binder resin. An undercoat layer may be provided for the purpose of improving the adhesion between the support and the recording layer and preventing the penetration of the recording layer material into the support. The same resin as the above-mentioned resin for the recording layer can be used for the intermediate layer and the undercoat layer.

A filler may be added to the undercoat layer, the recording layer, the intermediate layer, and the protective layer. The filler can be divided into an inorganic filler and an organic filler. As the inorganic filler, carbonates such as calcium carbonate and magnesium carbonate; silicates such as silicic anhydride, hydrous silicic acid, hydrous aluminum silicate and hydrous calcium silicate; hydroxides such as alumina and iron oxide; zinc oxide , Indium oxide, alumina, silica, zirconia oxide, tin oxide, cerium oxide, iron oxide, antimony oxide, barium oxide, calcium oxide, bismuth oxide, nickel oxide, magnesium oxide, chromium oxide, manganese oxide, tantalum oxide, niobium oxide, Metal oxides such as thorium oxide, hafnium oxide, molybdenum oxide, iron ferrite, nickel ferrite, cobalt ferrite, barium titanate, and potassium titanate; metal sulfides or sulfuric acid compounds such as zinc sulfide and barium sulfate; titanium carbide; Silicon Carver De, molybdenum carbide, tungsten carbide, metal carbides such as tantalum carbide; aluminum nitride, silicon nitride, boron nitride,
Zirconium nitride, vanadium nitride, titanium nitride,
Metal nitrides such as niobium nitride and gallium nitride are exemplified.

As the organic filler, silicone resin,
Cellulose resin, epoxy resin, nylon resin, phenol resin, polyurethane resin, urea resin, melamine resin, polyester resin, polycarbonate resin, styrene, polystyrene, styrene resins such as polystyrene / isoprene, styrene vinylbenzene, vinylidene chloride acrylic, acrylic urethane And acrylic resins such as ethylene acrylic, polyethylene resins, formaldehyde resins such as benzoguanamine formaldehyde and melamine formaldehyde, polymethyl methacrylate resins, and vinyl chloride resins. In the present invention, the organic filler can be used alone, but it may contain two or more kinds, or may be a composite particle. Examples of the shape include a spherical shape, a granular shape, a plate shape, and a needle shape.

The content of the filler in the layer is 1 to 95% by volume, more preferably 5 to 75%.

A lubricant may be added to the undercoat layer, the recording layer, the intermediate layer, and the protective layer. Specific examples of the lubricant include synthetic waxes such as ester wax, paraffin wax and polyethylene wax: hardened castor oil and the like. Vegetable waxes: animal waxes such as hardened tallow oil:
Higher alcohols such as stearyl alcohol and behenyl alcohol: higher fatty acids such as margaric acid, lauric acid, mystyrenic acid, palmitic acid, stearic acid, behenic acid, and furomenic acid: higher fatty acid esters such as sorbitan fatty acid esters: stearic acid amide And amides such as oleic acid amide, lauric acid amide, ethylenebisstearic acid amide, methylenebisstearic acid amide, and methylolstearic acid amide.

The content of the lubricant in the layer is from 0.1 to 0.1 in volume fraction.
It is 95%, more preferably 1 to 75%. The intermediate layer and the protective layer may contain an inorganic or organic ultraviolet absorber, and the content is preferably in the range of 0.5 to 10 parts by weight based on 100 parts by weight of the binder.

As the organic ultraviolet absorber, 2- (2'-
(Hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-
3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-
5′-methylphenyl) benzotriazole, 2-
(2'-hydroxy-5'-octoxyphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'
-Di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-t-butyl-
Benzotriazole ultraviolet absorbers such as 5'-methylphenyl) -5-chlorobenzotriazole and 2- (2'-hydroxy-5'-ethoxyphenyl) benzotriazole.

2,4-dihydroxybenzophenone, 2
-Hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2 ′
-Dihydroxy-4-methoxybenzophenone, 2,
2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-oxybenzylbenzophenone , 2-hydroxy-4-chlorobenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, sodium 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2,2 ′
Benzophenone ultraviolet absorbers such as dihydroxy-4,4'-dimethoxybenzophenone-sodium sulfonate;

Salicylate ester ultraviolet absorbers such as phenyl salicylate, p-octylphenyl salicylate, pt-butylphenyl salicylate, carboxyphenyl salicylate, methylphenyl salicylate, dodecylphenyl salicylate, 2-ethylhexylphenyl salicylate, homomenthylphenyl salicylate, etc. .

2-ethylhexyl-2-cyano-3,
3'-diphenyl acrylate, ethyl-2-cyano-
Cyanoacrylate ultraviolet absorbers such as 3,3'-diphenylacrylate; p-aminobenzoic acid, glyceryl p-aminobenzoate, amyl p-dimethylaminobenzoate, and p- such as ethyl p-dihydroxypropylbenzoate.
Aminobenzoic acid UV absorber.

Cinnamic acid-based ultraviolet absorbers such as 2-ethylhexyl p-methoxycinnamate and 2-ethoxyethyl p-methoxycinnamate; 4-t-butyl-4'-methoxy-dibenzoylmethane; And urocanic acid and ethyl urocanate.

Solvents used for coating liquids for the intermediate layer and the protective layer,
Known methods used for the recording layer can be used for the coating liquid dispersing apparatus, coating method, drying / curing method, and the like.

In order to form a color image using the reversible thermosensitive recording medium of the present invention, the color image may be heated once to a color development temperature and then rapidly cooled. In particular,
For example, if the recording layer is heated for a short time with a thermal head or laser light, the recording layer is locally heated, so that the heat is immediately diffused and rapid cooling occurs, so that the coloring state can be fixed. On the other hand, in order to erase the color, heating may be performed by using an appropriate heat source for a relatively long time to cool, or heating may be temporarily performed to a temperature slightly lower than the coloring temperature. If the recording medium is heated for a long time, the temperature of a wide area of the recording medium rises, and the subsequent cooling is slowed down. As a heating method in this case, a heat roller, a heat stamp, hot air, or the like may be used, or heating may be performed for a long time using a thermal head. In order to heat the recording layer to the decoloring temperature range, the applied energy may be slightly reduced from that at the time of recording, for example, by adjusting the voltage applied to the thermal head, the number of pulses, the pulse width, and the pulse interval. Using this method, recording and
Erasing is possible, so-called overwriting becomes possible. Of course, it can be erased by heating to a decoloring temperature range by a heat roller or a heat stamp.

The reversible thermosensitive recording medium of the present invention is formed by holding the recording layer on the support exemplified above.
The support used at this time can have a thickness as required, and can be used alone or by laminating. That is, a support having an arbitrary thickness from about several μm to about several mm is used. Further, these supports may have a magnetic recording layer on the same side and / or the opposite side as the reversible thermosensitive recording layer. The reversible thermosensitive recording medium of the present invention may be attached to another medium via an adhesive layer or the like. The reversible thermosensitive recording medium of the present invention may be processed into a sheet shape or a card shape, may be processed into any shape, and may be subjected to printing processing on the surface of the medium. The reversible thermosensitive recording medium of the present invention may use an irreversible thermosensitive recording layer in combination. At this time, the color tone of each recording layer may be the same or different.

[0132]

The present invention will be described in more detail with reference to the following examples. In the examples, “parts” and “%” are based on weight. <Example 1> 1) 2 parts of 2-anilino-3-methyl-6-dibutylaminofluoran 2) 8 parts of a developer having the following structure

[0133]

Embedded image 3) Decolorization accelerator of the following structure: 3 parts

[0134]

Embedded image

4) 70% of a 15% solution of acrylic polyol resin in tetrahydrofuran (THF) The above composition was averaged in a ball mill using a ball mill to have an average particle size of 0.1 to 3 μm.
m. 10 parts of Coronate HL (adduct type hexamethylene diisocyanate 75% ethyl acetate solution) manufactured by Nippon Polyurethane Co., Ltd. was added to the obtained dispersion,
The mixture was stirred well to prepare a recording layer coating solution. The recording layer coating solution having the above composition was applied to a 188 μm-thick polyester film using a wire bar, dried at 100 ° C. for 2 minutes, and then heated at 60 ° C. for 24 hours to form a film having a thickness of about 8.0 μm. A recording layer was provided to produce a reversible thermosensitive recording medium of the present invention.

Example 2 A reversible thermosensitive recording medium was produced in the same manner as in Example 1 except that the following decolorization accelerator was used instead of the decolorization accelerator in Example 1. [Decoloring accelerator]

[0137]

Embedded image

<Example 3> A reversible thermosensitive element was prepared in the same manner as in Example 1 except that the following developer and decolorizer were used in place of the developer and decolorizer in Example 1. A recording medium was produced. [Developer]

[0139]

Embedded image [Decoloring accelerator]

[0140]

Embedded image

<Example 4> A reversible thermosensitive recording medium was prepared in the same manner as in Example 3, except that the following decolorization accelerator was used instead of the decolorization accelerator in Example 3. [Decoloring accelerator]

[0142]

Embedded image

Example 5 A reversible thermosensitive recording medium was obtained in the same manner as in Example 1, except that the dispersion of Example 1 was changed to the following composition. 1) 2-anilino-3-methyl-6-dibutylaminofluorane 2 parts 2) Color developer having the following structure 8 parts

[0144]

Embedded image 3) 1 part of decolorization accelerator having the following structure

[0145]

Embedded image 4) Color-decoloring control agent having the following structure: 3 parts

[0146]

Embedded image 5) 70 parts of 15% tetrahydrofuran (THF) solution of acrylic polyol resin

<Example 6> A reversible thermosensitive recording medium was produced in the same manner as in Example 5, except that the following decolorization accelerator was used instead of the decolorization accelerator in Example 5. [Decoloring accelerator]

[0148]

Embedded image

<Example 7> A reversible thermosensitive recording medium was prepared in the same manner as in Example 5, except that the following decolorization accelerator was used in place of the decolorization accelerator in Example 5. [Decoloring accelerator]

[0150]

Embedded image

<Example 8> A reversible thermosensitive recording medium was produced in the same manner as in Example 5, except that the following decolorization accelerator was used in place of the decolorization accelerator in Example 5. [Decoloring accelerator]

[0152]

Embedded image

<Comparative Example 1> A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that the following color developer was used in place of the color developer in Example 1 and no decolorizing accelerator was used. Was prepared. [Developer]

[0154]

Embedded image

Comparative Example 2 A reversible thermosensitive recording medium was produced in the same manner as in Example 1 except that the following decolorization accelerator was used instead of the decolorization accelerator in Example 1. [Decoloring accelerator]

[0156]

Embedded image The reversible thermosensitive recording medium produced as described above was printed at a voltage of 13.3 V and a pulse width of 1.2 msec with a thermal printing apparatus manufactured by Okura Electric Co., Ltd., and the obtained image was measured with a Macbeth densitometer RD-914. did. The color image was erased with a thermal gradient tester manufactured by Toyo Seiki Co., Ltd. under the conditions of 110 ° C. for 1 second, and the density of the image portion after the color was erased and the background density were measured. Next, the remaining density was calculated from the following equation. The lower the remaining erase density, the lower the density with the same energy, and the faster the erase.

[0157]

(Equation 1)

Next, the densities of the obtained image portion and the background portion were measured, and measured as the image density before the test and the background density before the test, respectively. The sample was stored under a drying condition of 50 ° C. for 24 hours. The densities of the image portion and the background portion are measured and defined as a post-test image density and a post-test image background density, respectively. Next, the concentration retention was calculated from the following equation.

[0159]

(Equation 2)

Table 21 shows the above results.

[0161]

[Table 21]

<Example 9> A protective layer having the following composition was provided on the recording layer prepared in Example 7 to prepare a reversible thermosensitive recording medium. [Preparation of protective layer] 1) 15 parts of urethane acrylate ultraviolet curable resin (C7-157, manufactured by Dainippon Ink) 2) 85 parts of ethyl acetate The above composition is dissolved and stirred well to prepare a coating liquid for protective layer. did. The protective layer coating solution having the above composition was coated on the recording layer using a wire bar, dried at 90 ° C. for 1 minute, and then transferred under an ultraviolet lamp having an irradiation energy of 80 W / cm at a transport speed of 9 m / min. The protective layer having a thickness of 3 μm was provided by curing the recording medium to form a reversible thermosensitive recording medium of the present invention.

Example 10 A protective layer was provided on the recording layer prepared in Example 8 in the same manner as in Example 7 to produce a reversible thermosensitive recording medium. When the reversible thermosensitive recording medium produced in Example 9 and Example 10 was repeated 50 times under the above-described color forming condition and decoloring condition, the reversible thermosensitive recording medium of Example did not have occurrence of dents and the like. Good coloring and decoloring density were maintained.

<Comparative Example 3> Instead of the acrylic polyol resin used in Example 7, 120 parts of a 15% MEK solution of polyvinyl chloride-vinyl acetate resin (VYHH manufactured by Union Carbide Co.) was used, and the recording layer was used without using Coronate HL. Then, instead of the protective layer used in Example 9, a polyvinyl chloride-vinyl acetate (VYHH manufactured by Union Carbide) MEK solution was used and dried at 100 ° C. for 3 minutes to form a protective layer having a thickness of about 3 μm. A reversible thermosensitive recording medium was produced in the same manner as in Example 9 except that the recording medium was provided.

When the reversible thermosensitive recording medium produced in Comparative Example 3 was repeated 50 times under the above-described color-forming and decoloring conditions, the reversible thermosensitive recording medium was susceptible to occurrence of dents and uniform image quality. Coloring and erasing could not be performed.

Example 11 An intermediate layer having the following composition was provided on the recording layer prepared in Example 7. [Preparation of Intermediate Layer] 30 parts of 15% methyl ethyl ketone (MEK) solution of acrylic polyol resin Viosorb 130 (2-hydroxy-4-n-octoxy) benzophenone 4 parts manufactured by Kyodo Chemical Co. 4 parts Coronate HL 4 parts 100 ° C, 2
After drying for 2 minutes, the film was heated at 60 ° C. for 24 hours and the film thickness was 2 μm
Was provided. Next, a protective layer was provided in the same manner as in Example 9 to obtain a reversible thermosensitive recording medium of the present invention.

Example 12 An intermediate layer was provided on the recording layer prepared in Example 8 in the same manner as in Example 11. Further, a protective layer was provided in the same manner as in Example 9 to obtain a reversible thermosensitive recording medium of the present invention.

As described above, Embodiment 11 and Embodiment 12
After coloring the reversible thermosensitive recording medium prepared in the above under the same coloring conditions as above, irradiating with a fluorescent lamp 5000lux for 100 hours, then erasing under the same erasing conditions as above, and examining the deterioration due to light, No change was observed in the image area after light irradiation, and the image was in a good state without any erasure after erasure.

[0169]

As described above, the reversible thermosensitive recording medium of the present invention has excellent high-speed erasability, and further has excellent storage stability, durability and light resistance. This is an extremely excellent effect.

[Brief description of the drawings]

FIG. 1 is a diagram showing color development / decoloration characteristics of a reversible thermosensitive recording medium of the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaru Shimada 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H026 AA07 AA09 BB06 BB15 BB25 DD03 DD43 DD45 DD46 DD53 DD55 FF05 FF11 FF17 FF25

Claims (12)

[Claims] Claims 1. An electron-donating color-forming compound and an electron-accepting compound are used on a support, and a state in which color is relatively developed and a state in which color is erased due to a difference in heating temperature and / or cooling rate after heating. In a reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing a reversible thermochromic composition which can be formed, the following general formula (I) is used as a decolorizing accelerator in the reversible thermosensitive recording layer.
A reversible thermosensitive recording medium comprising a compound represented by the formula: Embedded image In the formula (I), n represents an integer of 2 to 4, and R ₁ represents a bond or a hydrocarbon group having 1 to 6 carbon atoms. Similarly, R ₂ represents a hydrocarbon group having 1 to 20 carbon atoms.
Further, X represents a divalent group containing a hetero atom. However, a plurality of R ₁ , R ₂ and X generated by n may be different. 2. The compound represented by the formula (I) is represented by n
2. The reversible thermosensitive recording medium according to claim 1, wherein the compound is a compound represented by the following formula (II): Embedded image In the formula (II), R ₁₁ and R ₂₁ each independently represent a bond or a hydrocarbon group having 1 to 6 carbon atoms. Similarly, R ₁₂ and R ₂₂ each independently represent a hydrocarbon group having 1 to 20 carbon atoms. Further, X ₁ and X ₂ each independently represent a divalent group containing a hetero atom. 3. The compound represented by the formula (II) is represented by the structure of the following formula (III):
4. The reversible thermosensitive recording medium according to item 1. Embedded image In the formula (III), R ₁₁ and R ₂₁ each independently represent a bond or a hydrocarbon group having 1 to 6 carbon atoms. Similarly, R ₁₂ and R ₂₂ each independently represent a hydrocarbon group having 1 to 20 carbon atoms. Further, X ₁ and X ₂ each independently represent a divalent group containing a hetero atom. 4. The reversible thermosensitive recording medium according to claim 1, wherein the reversible thermosensitive recording layer contains a crosslinked resin. 5. The reversible thermosensitive recording medium according to claim 1, wherein a phenol compound having an alkyl chain having 8 or more carbon atoms is used as the electron accepting compound. 6. The compound according to claim 1, wherein a compound having a divalent group containing a hetero atom and an alkyl chain having 6 or more carbon atoms is used as the coloring and decoloring accelerator.
4. The reversible thermosensitive recording medium according to item 1. 7. The reversible thermosensitive recording medium according to claim 4, wherein the resin in a crosslinked state is a resin in a crosslinked state with an isocyanate, and the resin is in a crosslinked state with an isocyanate compound. 8. The reversible thermosensitive recording medium according to claim 1, wherein a layer containing an inorganic or organic ultraviolet absorber is provided on the recording layer. 9. The reversible thermosensitive recording medium according to claim 1, wherein a layer using a crosslinked resin is provided as a protective layer on the recording layer. 10. The reversible thermosensitive recording medium according to claim 1, further comprising a magnetic recording layer. 11. The reversible thermosensitive recording medium according to claim 1, wherein the medium is processed into a card shape or a sheet shape. 12. The printing apparatus according to claim 1, wherein at least a part of the front surface and / or the back surface has a printed portion.
2. The reversible thermosensitive recording medium according to any one of 1.